PRL and Galactorrhea: To explain this undesirable effect, it is necessary to understand that galactorrhea seems to be mediated by the serotonergic activation of prolactin-releasing factors, such as the thyrotropin-releasing hormone of the postsynaptic 5HT receptors of the hypothalamus, and/or by the serotonergic inhibition of prolactin-releasing hormone (PRL)-releasing factors such as dopamine, or indirectly via the release of oxytocin or vasoactive intestinal peptide [3].